Optical system for shaping the wavefront of the electric field of an input light beam

Abstract

An optical system for shaping a wavefront of an electric field of an input light beam to be projected into a target volume including a first optical element, a spatial light modulator used to control light distribution in at least one transverse plane in the target volume. An intermediate optical element located on an optical axis, after the first optical element on a trajectory of the light beam for modulating the phase or the amplitude of the electric field of the input light beam is included. A second optical element for modulating the phase or the amplitude of the electric field of the input light beam is used to control the axial position of the transverse plane in the target volume. The second optical element is situated on the optical axis after the at least one intermediate optical element on the trajectory of the light beam.

The invention claimed is: 
     
       1. An optical system for shaping a wavefront of an electric field of a light beam ( 1 ) to be projected into a target volume ( 5 ), for realizing multi (3D)-transversal plane illumination patterns along the optical axis (z) in a target volume, including:
 (i) a first optical element ( 2 ) which is a spatial light modulator used to control light distribution, through phase or amplitude modulation of the electric field of the light beam, forming 2D illumination patterns in at least one transverse plane ( 51 ,  52 ,  53 ) in the target volume ( 5 ) in regard to an optical axis (z), a first spatial light modulator being divided in a number of first independent regions ( 21 ,  22 ), each of these first independent regions ( 21 ,  22 ) being used to generate a 2D illumination pattern ( 511 ,  521 ) focused onto at least one intermediate optical element ( 4 ,  4   a ,  4   b ), 
 (ii) the at least one intermediate optical element ( 4 ,  4   a ,  4   b ) being a dispersive grating having lines for performing temporal focusing of the light beam ( 1 ) on the at least one transverse plane ( 51 ,  52 ,  53 ), and being located, on the optical axis (z), after the first optical element ( 2 ) on a trajectory of the light beam ( 1 ) where an image of the 2D illumination patterns is formed, for modulating the phase or the amplitude of the electric field of the light beam, 
 (iii) and a second optical element ( 3 ) being a spatial light modulator for modulating the phase of the electric field of the input light beam and used to control an axial position of the at least one transverse plane ( 51 ,  52 ,  53 ) in the target volume ( 5 ) along the optical axis (z), the second optical element ( 3 ) being situated on the optical axis (z) after the at least one intermediate optical element ( 4 ) on the trajectory of the light beam ( 1 ) at a plane conjugated to the at least one intermediate optical element ( 4 ,  4   a ,  4   b ), the second optical element ( 3 ) being divided in a number of second independent regions ( 31 ,  32 ) equal to the number of first independent regions ( 21 ,  22 ), each second independent region ( 31 ,  32 ) controlling the axial position in the target volume ( 5 ) of the corresponding 2D illumination patterns ( 511 ,  521 ) generated by the first spatial light modulator in the transverse planes ( 51 ,  52 ), the transverse planes ( 51 ,  52 ) being displaced independently of each other in regard to the optical axis (z) in the target volume, the number of first independent regions ( 21 ,  22 ) being equivalent to the number of transverse planes ( 51 ,  52 ), the first independent regions and the second independent regions ( 21 ,  22 ,  31 ,  32 ) are tiled parallel to an orientation of the dispersive grating lines. 
 
     
     
       2. The optical system according to  claim 1 , wherein the optical system comprises at least two intermediate optical elements ( 4 ) and wherein:
 a first intermediate optical element ( 4   a ) is located at a Fourier plane of a first lens ( 6 ) situated between the first optical element ( 2 ) and the first intermediate optical element ( 4   a ), and 
 a last intermediate optical element ( 4   b ) is located at a back focal plane of a second lens ( 7 ) situated between the last intermediate optical element ( 4   b ) and the second optical element ( 3 ), such that the second optical element ( 3 ) is located at a Fourier plane of the second lens ( 7 ). 
 
     
     
       3. The optical system according to  claim 1 , wherein the optical system comprises at least two intermediate optical elements ( 4 ) and wherein:
 a first intermediate optical element ( 4   a ) is located at a Fourier plane of a first lens ( 6 ) situated between the first optical element ( 2 ) and the first intermediate optical element ( 4   a ), and 
 a last intermediate optical element ( 4   b ) is located at a plane that is conjugated to the plane of the first intermediate optical element through a telescope formed by two lenses ( 8   a ) and ( 8   b ). 
 
     
     
       4. The optical system according to  claim 1 , wherein the optical system comprises two intermediate optical elements, the first intermediate optical element being a digital micromirror device (DMD) and the second intermediate optical element being a dispersive grating. 
     
     
       5. The optical system according to  claim 1 , wherein the optical system comprises one intermediate optical element ( 4 ) and wherein the intermediate optical element ( 4 ) is located at a Fourier plane of a first lens ( 6 ) situated between the first optical element ( 2 ) and the at least one intermediate optical element ( 4 ). 
     
     
       6. The optical system according to  claim 1 , wherein the optical system comprises one single intermediate optical element, which is a digital micromirror device for fast amplitude modulation of the illumination patterns in the at least one transverse plane and wherein the first independent regions and second independent regions ( 21 ,  22 ,  31 ,  32 ) are tiled vertically or horizontally relatively to the planes of the optical elements ( 2 , 3 ). 
     
     
       7. The optical system according to  claim 1 , wherein the second optical element ( 3 ) is located at a back focal plane of a third lens ( 9   a ), which, together with a fourth lens ( 9   b ), form a telescope to image the plane of the second optical element ( 3 ) to a back focal plane of an objective lens ( 10 ). 
     
     
       8. The optical system according to  claim 1 , wherein the second optical element ( 3 ) is a phase spatial light modulator programmed to compensate for optical aberrations introduced by elements located after the last intermediate optical element on the optical axis. 
     
     
       9. The optical system according to  claim 1 , wherein the second spatial light modulator ( 3 ) is being operatively addressed with cropped spherical phase functions in each second independent region ( 31 ,  32 ).